Conservatives and Liberal Democrats urged to return £520,000 bequest

Parties' decision to take money bequeathed to 'whichever government is in office' described as 'dodgy as hell'

The parties led by David Cameron and Nick Clegg claim they were told by Edwards’s executors that she wanted her money to go to whoever was governing the country at the time of her death. Photograph: Tim Ireland/PA

The Conservatives and Liberal Democrats are under pressure to hand back a £520,000 donation bequeathed to "whichever government is in office" by an elderly woman in her will.

The decision to take the money for political purposes was branded as "dodgy as hell" because Joan Edwards would have been more likely to want the cash to go to the nation.

The parties claim they were told by Edwards's executors that she wanted her money to go to whoever was governing the country at the time of her death. They split the donation between them according to their size in parliament, with the Tories getting around £420,000 and the Liberal Democrats about £100,000.

However, a copy of her will was tracked down by the Daily Mail, which found it should go to "whichever government is in office at the date of my death for the government in their absolute discretion to use as they may think fit".

Records show Joan Lilian Edwards was born in Bristol in 1921, never married and lived there all her life working variously as a nurse and midwife. She had lived in a three-bedroom council house in the city since 1931 until her death last year.

Friends told the Mail that she had never appeared to show interest in politics and would have wanted the government to do something good with her money.

Edwards, who lived in Fishponds, a residential area about three miles from the city centre, died on 22 September last year.

Joan Edwards' will

Her will was drawn up in September 2001 with her executors named as the partners of a local law firm, Davis Wood. It was signed by Edwards in neat, old-fashioned writing.

The will left instructions for any debts, her funeral and expenses and fees relating to sorting out her affairs to be paid. It said anything else was to go to "whichever government is in office at the date of my death for the government in their absolute discretion to use as they may think fit".

Peter Wood, one of the partners who acted as executor, said on Tuesday: "I'd love to more helpful but I'm going to have to say I have no comment at the moment. I really can't take it any further."

Asked about the suggestion that it was the executors' interpretation that the money should go to the parties, Wood said: "I'd be getting into areas I don't want to comment. I have read all of that. I can't take it any further."

On Wednesday morning, several Labour politicians called for the parties to return the money.

Lord Prescott, the former deputy prime minister, said the Tories and Lib Dems "must hand back the £500k Joan Edwards left to the nation", and started a campaign to work out what to do with "Joan's half million".

Meanwhile Jim Murphy, the shadow defence secretary, called for more investigation.

"Unless [the] explanation of this is much clearer [and] more credible this looks dodgy as hell by Tories [and] Libs," he tweeted.

Alistair Graham, former chairman of the committee on standards in public life, also said the parties should give the money back.

He said they "seem to have very quickly distributed the loot between the two of them" without conducting enough checks.